Why my blender user preferences input panel is blank?
Try resetting them to factory defualts:


  1) To reset interface AND the current opened file: File > Load Factory
  Settings;
  2) To open a file without loading its interface: File>
  Open, then untick the "Load UI" in the left of the File Browser
  window. 
  
  Ctrl+U saves the current file as Blender default file (the one seen
  when Blender is opened). 
  
  Seen at:
  http://blenderartists.org/forum/showthread.php?t=202110&amp;page=1


Or try updating your version of blender by installing the most recent version:


  http://www.blender.org/download/


Hope that helps! :)